Jackie Onassis believed that Lyndon B Johnson and a cabal of Texas tycoons were involved in the assassination of her husband John F Kennedy, ‘explosive’ recordings are set to reveal.

The secret tapes will show that the former first lady felt that her husband’s successor was at the heart of the plot to murder him.

She became convinced that the then vice president, along with businessmen in the South, had orchestrated the Dallas shooting, with gunman Lee Harvey Oswald – long claimed to have been a lone assassin – merely part of a much larger conspiracy.

Texas-born Mr Johnson, who served as the state’s governor and senator, completed Mr Kennedy’s term and went on to be elected president in his own right.

The tapes were recorded with leading historian Arthur Schlesinger Jnr within months of the assassination on November 22, 1963, and had been sealed in a vault at the Kennedy Library in Boston.

The then Mrs Kennedy, who went on to marry Greek shipping tycoon Aristotle Onassis, had ordered that they should not be released until 50 years after her death, with some reports suggesting she feared that her revelations might make her family targets for revenge.

She died 17 years ago from cancer aged 64 and now her daughter, Caroline Kennedy, has agreed to release the recordings early.